As the size of semiconductor devices continues to shrink, it has been necessary for the thickness of the dielectric layers utilized in these devices to shrink as well. Consequently, the accurate measurement of the thickness of dielectric films has become an important aspect of microelectronic device development, simulation, and manufacturing.
Currently, various techniques are known to the art for measuring film thicknesses. These include Transmission Electron Microscopy (TEM), X-ray Photoelectron Spectroscopy (XPS), medium-energy ion scattering spectrometry (MEIS), Rutherford Backscattering Spectrometry (RBS), Secondary Ion Mass Spectrometry (SIMS), Auger Electron Spectroscopy (AES), and ellipsometry. However, when film thicknesses fall below about 20 Å (as is frequently the case with currently emerging technologies), the accuracy with which these thicknesses may be measured is a challenge for existing measurement techniques.
There is thus a need in the art for methods and devices for measuring film thicknesses, and especially those of thin film dielectric layers. In particular, there is a need in the art for a method for accurately measuring the thickness of dielectric films (such as SiO2 films) when the thickness of those films falls below 20 Å. These and other needs may be met by the devices and methodologies disclosed herein.